TT4 digi w/Maxtrac

[W5KVV]

Has anyone on the forums successfully built a digi using a Tiny Trak 4 and a Motorola Maxtrac?

I have everything ready to go, cable built using the 16 pin on the radio. The TT4 will TX fine, but I can not make it hear anything. The Maxtrac is configured properly, Pin 8 is set to carrier detect, output, debounce no, active low. The radio is passing RX audio as measured with an O scope.

The problem is on the TT4 side. It will not hear anything. I've tried changing the settings on the TT4 till I'm blue in the face.

Any help would be appreciated.

 

[wa8pyr]

Has anyone on the forums successfully built a digi using a Tiny Trak 4 and a Motorola Maxtrac?

I have everything ready to go, cable built using the 16 pin on the radio. The TT4 will TX fine, but I can not make it hear anything. The Maxtrac is configured properly, Pin 8 is set to carrier detect, output, debounce no, active low. The radio is passing RX audio as measured with an O scope.

The problem is on the TT4 side. It will not hear anything. I've tried changing the settings on the TT4 till I'm blue in the face.

Any help would be appreciated.

Two things I can think of off the top of my head. . .

1. The audio level coming from Pin 11 (the discriminator audio output pin) may not be high enough for the TT4 to use.

2. Are you running 1200 baud or 9600 baud? If 9600 baud, make sure the jumper (JU551) in the radio is set to flat audio so you bypass the deemphasis circuit. This will help 1200 baud also, but it's not such an issue at 1200.

Very useful info: http://www.repeater-builder.com/motorola/maxtrac/maxtrac-option-plug.html

Also very useful: http://www.qsl.net/kb8qeu/MaxTrac_GM300/Maxtrac_to_TinyTrak3.html

It states the RX audio line is not needed if you use Carrier Detect for channel activity although I'm scratching my head over that one; Carrier Detect is high/low and merely indicates there's an active carrier present. Where is the TT4 getting its input audio from?